I have a healthy male Dwarf gourami but I have lost three females, all of which have wasted away. He doesn’t seem to be bullying them — they just seem to become skinny, stop eating and then hang about in one corner of the tank. I’m not inclined to try another, so will he be OK on his own — or should these fish really have a mate?LYNN WOODS, EMAIL

Dwarf gouramis are an old aquarium favourite, and rightly so given the lovely colour displayed by the males. Native to India, Pakistan and Bangladesh, the fish seen in the hobby are largely commercially produced in Singapore. Sadly many of these fish are plagued by a nasty disease known as ‘Dwarf gourami iridovirus’, some of the symptoms of which are similar to those you describe seeing in the females you have lost. This disease is untreatable, but the fact that the male is unaffected could be down to a natural immunity.

However, the males of this species are also well known for bullying and pestering females, especially if the tank is too small or doesn’t offer enough cover in the form of dense vegetation.

Lush floating plants are ideal for this, allowing females to hide away from the male’s unwanted attentions. As you have already lost three females it seems to me that even though you haven’t noticed any bullying it is still the most likely cause of their demise. A well-established healthy male will see each new female as a potential mate and immediately begin trying to impress her, regardless of her condition.

This probably means the new fish have no time to settle in and feed up and simply fade away.

My advice is to keep the male by himself. He won’t suffer from being kept alone and you’ll be able to enjoy his gorgeous colouration without worrying about a harassed and sickly female.BOB MEHEN